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A 66-year-old man with a history of bilateral carpal tunnel syndrome was evaluated for chronic joint pain and stiffness involving the shoulders, hips, and knees over the past 6 years. He had no fever, skin rash, headaches, vision changes, or urinary symptoms. He reported occasional bruising around his eyes. His only medication was acetaminophen as needed for pain. His vital signs were normal. No joint tenderness, warmth, or fluid collections were present, and skin examination was normal. The presence of raised soft tissue masses around the sternoclavicular joints (Figure, left panel) and scapulae (Figure, right panel) were noted. Laboratory evaluation revealed normal results for complete blood cell count, erythrocyte sedimentation rate (ESR), and levels of electrolytes, creatinine, and C-reactive protein. A spot urinalysis showed a protein level of 220 mg/dL (reference range, <26 mg/dL), and a 24-hour urine collection revealed 1.8 g of albumin (reference range, <229 mg/24 h). Magnetic resonance imaging (MRI) of the shoulders and hips showed synovial and capsular thickening.
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Light-chain amyloidosis with joint and kidney involvement.
B. Order serum protein electrophoresis and serum free light chains assay
The key to the correct diagnosis is the presence of chronic joint pains associated with soft tissue masses, along with the history of bilateral carpal tunnel syndrome, periorbital purpura, and significant albuminuria, which should trigger consideration of light-chain amyloidosis. Inflammatory arthritis and vasculitis may present similarly; however, ESR, C-reactive protein level, or both are typically elevated.1- 3 Giant cell (temporal) arteritis is less likely in this patient because of lack of headache or vision changes; thus, a temporal artery biopsy would not be diagnostic, although it may reveal amyloid deposits if the specimen was appropriately stained. Bone scan results would not be specific for a diagnosis in this case, and starting methotrexate is premature.
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Corresponding Author: Morie A. Gertz, MD, MACP, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (firstname.lastname@example.org).
Published Online: September 5, 2019. doi:10.1001/jama.2019.12704
Conflict of Interest Disclosures: Dr Gertz reported receiving personal fees from Akcea, Alnylam, and Prothena outside the submitted work. No other disclosures were reported.
Additional Contributions: We thank the patient for providing permission to share his information.
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